Vehicle operators and consumers express the need and desire for reduced levels of noise such as road noise, engine noise, vibrations, etc. within a vehicle passenger compartment. Accordingly, sound attenuating materials and paneling are conventionally used throughout the vehicle such as in the dashboard and floor panels to reduce the noise, vibration, and harshness (NVH) in the vehicle passenger compartment.
In addition to materials and paneling that reduce the levels of noise in a passenger cabin, these materials may also be required to provide efficient thermal insulation. When paneling is used in the dashboard to separate the engine compartment and the passenger compartment, thermal insulating materials that can withstand the high temperatures emitted from the engine are required. The design of such noise and temperature insulating panels can be difficult since it can be a careful balance to engineer panels that offer proper dual insulating capabilities. For example, many foam materials that would make a good sound absorber will readily melt at the elevated temperatures found in an engine compartment.
As fuel economy and emission requirements continually become more restrictive for original equipment manufacturers (OEMs), the reduction of displacement in engines is becoming common place. In many instances, OEMS are using turbo chargers to increase both the horse power and torque of smaller displacement engines. A consequence of using smaller, higher revving engines is they often generate more heat, especially heat that is generated by the turbo chargers. In many instances, the highest amount of heat generated in an engine compartment is found within the first fifteen minutes after the engine has been turned off and the air circulation and cooling systems have been deactivated. These conditions require the need for paneling and lower cowl structures such as extension dash panels to offer both noise and thermal insulation for the occupants in the passenger compartment.